There are numerous applications that exist where two members are attached to each other through a vibration damping device. These applications include automobile body mounts, subframe mounts, cradle mounts, engine mounts and the like. The vibration damping devices dampen or isolate vibrations (including noises induced by the vibrations) between the two members.
A fluid filled active vibration damping device has been proposed as one type of such vibration damping devices. The fluid filled device includes a first mounting member adapted to be attached to one of the two members; a second mounting member adapted to be attached to the other of the two members; an elastic body connecting the first and the second mounting members; a pressure-receiving chamber partially defined by the elastic body and filled with a non-compressible fluid; an equilibrium chamber partially defined by a flexible layer and filled with the non-compressible fluid; and an orifice passage permitting fluid communication between the pressure-receiving chamber and the equilibrium chamber. This fluid filled damping device is capable of exhibiting a desired vibration-damping effect on the basis of flows of the fluid through the orifice passage.
Generally, a fluid filled vibration-damping device is capable of damping vibrations in one direction which is generally in an axial direction with respect to the device. While this may be acceptable for a vibration-damping device when it is used as an engine mount, when these vibration-damping devices are used elsewhere in the vehicle, additional damping characteristics are needed for tuning the “noise, vibration and harshness” of the vehicle, especially when mounting a cab or a body on a frame.